Predictive capabilities of Vibration-Correlation Technique applied to axially compressed CFRP truncated cones

Abstract

The paper deals with the application of the non-destructive Vibration-Correlation Technique (VCT) to estimate the buckling load of thin-walled, unstiffened CFRP truncated cones. After validating the structural response, detailed attention was devoted to assessing the predictive capabilities of the VCT for two conical structures at different load levels. In addition, parametric studies were carried out considering changes in the nominal bottom radius, the semi-vertex angle and the length of the cone. Two FE models were defined in the numerical analyses that accurately and roughly model the boundary conditions during compression. The measured initial mid-surface and thickness imperfections were taken into account in the numerical models. The results of the conducted study showed a slightly higher sensitivity of the VCT to ply topology design and to the scheme of initial imperfections it generates than it can be seen only on the basis of the structural response. Parametric studies revealed considerable conservativeness of the predictions provided by the use of VCT (99.93% of considered cases). The influence of thickness imperfection was found to be insignificant. In general, an increase in the maximum load level under consideration correlated with an increase in the predictive capabilities of the VCT and a decrease in divergence from the nonlinear buckling load.